Electrosurgical system

Abstract

An electrosurgical system includes an electrosurgical generator to which the active and return electrodes ( 18, 20 ) of an electrosurgical instrument ( 12 ) are connected. In use the electrodes are immersed in electrically-conductive fluid to complete a conduction path between them. The electrodes ( 18, 20 ) are located on a shaft ( 16 ) of the instrument which extends from a handle ( 14 ). The shaft is covered in a translucent flexible sheath ( 50 ) comprising a tube ( 60 ) having a large proximal opening ( 62 ) to enable insertion of the instrument within the sheath, and a narrower distal opening ( 64 ) through which the distal end of the instrument shaft projects, thereby to expose the active electrode ( 18 ) to the electrically-conductive fluid. Suction is applied to the interior of the sheath at an outlet port ( 66 ), and a seal ( 72 ) at the proximal end of the tube cooperates with a proximal surface ( 74 ) on the instrument handle to form a fluid-tight seal so that the suction is transmitted to the distal opening, in order to suck bubbles and debris away from the region around the active electrode ( 18 ). The distance between the active electrode ( 18 ) and the distal opening ( 64 ) of the tube ( 60 ) is chosen so that sufficient bubbles are sucked from the region around the active electrode to enable clear viewing of a treatment site without causing the resultant flow of conducting fluid over the active electrode to quench a vapor pocket which is formed around the active electrode when the instrument ( 12 ) is used to vaporize tissue.

What is claimed is:  
     
       1. An electrosurgical system comprising an electrosurgical instrument having a handle defining a proximal end of the instrument and by means of which the instrument may be manipulated by a user, a shaft extending from the handle; and an active tissue treatment electrode on the shaft which is axially spaced from the handle and which defines a distal end of the instrument; the system further comprising an elongate removable sheath adapted to extend coaxially with, and externally around, the shaft of the instrument, the sheath comprising an outlet port, an opening on the distal side of the outlet port, and sealing means on the proximal side of the outlet port for forming a substantially fluid-tight seal with the instrument, thereby to enable low pressure applied at the outlet port to be transmitted to the distal opening to create suction in the region thereof, wherein the sheath has a first cross-sectional area adjacent to the distal opening, a second cross-sectional area larger than the first cross-sectional area adjacent to the outlet port, and an intermediate section extending axially between the first cross-sectional area and the second cross-sectional area, at least the majority of the intermediate section having an intermediate cross-sectional area that is greater than the first cross-sectional area and smaller than the second cross-sectional area and that extends a majority of the distance between the outlet port and the distal opening. 
     
     
       2. An electrosurgical system according to  claim 1 , wherein the sheath has a larger internal cross-sectional area adjacent to the outlet port than at the distal opening. 
     
     
       3. An electrosurgical system according to  claim 1 , further comprising a valve for regulating suction at the outlet port. 
     
     
       4. An electrosurgical system according to  claim 1 , wherein the sealing means includes a sealing member located within the sheath and extending transversely to the shaft of the instrument, the sealing member having a substantially central aperture through which the shaft of the instrument projects, and forming a substantially fluid-tight seal with the shaft. 
     
     
       5. An electrosurgical system according to  claim 4 , wherein the member is made of an elastomeric material. 
     
     
       6. An electrosurgical system according to  claim 1 , further comprising an abutment including mutually-engageable surfaces in the instrument and the sheath, wherein when the mutually-engageable surfaces are in engagement, the distal opening of the sheath is located at a predetermined distance from the active electrode. 
     
     
       7. An electrosurgical system according to  claim 6 , wherein the mutually-engageable surfaces are at the proximal end of the sheath and the distal end of the handle. 
     
     
       8. An electrosurgical system according to  claim 1 , wherein the instrument further comprises a return electrode on the shaft and electrically insulated from the active electrode. 
     
     
       9. An electrosurgical system according to  claim 1 , wherein the intermediate section has a cross-sectional area that continuously tapers down from the second cross-sectional area adjacent to the outlet port to the first cross-sectional area adjacent to the distal opening. 
     
     
       10. An electrosurgical system according to  claim 1 , wherein the sealing means is such that the sheath is movable axially relative to the instrument while maintaining the integrity of the seal with the instrument. 
     
     
       11. An electrosurgical system according to  claim 1 , wherein the sheath tapers from the outlet port to the distal opening. 
     
     
       12. An electrosurgical system according to  claim 1 , wherein the sheath has a stepped internal cross-section. 
     
     
       13. An electrosurgical system comprising: 
       an electrosurgical instrument having a handle defining a proximal end of the instrument and by means of which the instrument may be manipulated by a user;  
       a shaft extending from the handle;  
       an active tissue treatment electrode on the shaft which is axially spaced from the handle and which defines a distal end of the instrument; and  
       an elongate removable sheath adapted to extend coaxially with, and externally around, the shaft of the instrument, the sheath comprising an outlet port, an opening on the distal side of the outlet port, and sealing means on the proximal side of the outlet port for forming a substantially fluid-tight seal with the instrument, thereby to enable low pressure applied at the outlet port to be transmitted to the distal opening to create suction in the region thereof;  
       wherein the sheath has a first cross-sectional area adjacent to the distal opening, a second cross-sectional area larger than the first cross-sectional area adjacent to the outlet port, and an intermediate section extending axially between the first cross-sectional area and the second cross-sectional area, at least the majority of the intermediate section having an intermediate cross-sectional area that is greater than the first cross-sectional area and smaller than the second cross-sectional area;  
       wherein the sealing means includes a sealing member located within the tube and extending transversely to the shaft of the instrument, the sealing member having a substantially central aperture through which the shaft of the instrument projects, and forming a substantially fluid-tight seal with the shaft; and  
       wherein the sealing member has the form of a web.  
     
     
       14. An electrosurgical system comprising: 
       an electrosurgical instrument having a handle defining a proximal end of the instrument and by means of which the instrument may be manipulated by a user;  
       a shaft extending from the handle;  
       an active tissue treatment electrode on the shaft which is axially spaced from the handle and which defines a distal end of the instrument; and  
       an elongate removable sheath adapted to extend coaxially with, and externally around, the shaft of the instrument, the sheath comprising an outlet port, an opening on the distal side of the outlet port, and sealing means on the proximal side of the outlet port for forming a substantially fluid-tight seal with the instrument, thereby to enable low pressure applied at the outlet port to be transmitted to the distal opening to create suction in the region thereof;  
       wherein the sheath has a first cross-sectional area adjacent to the distal opening, a second cross-sectional area larger than the first cross-sectional area adjacent to the outlet port, and an intermediate section extending axially between the first cross-sectional area and the second cross-sectional area, at least the majority of the intermediate section having an intermediate cross-sectional area that is greater than the first cross-sectional area and smaller than the second cross-sectional area;  
       wherein the sealing means includes a sealing member located within the tube and extending transversely to the shaft of the instrument, the sealing member having a substantially central aperture through which the shaft of the instrument projects, and forming a substantially fluid-tight seal with the shaft; and  
       wherein the sealing member has the form of a diaphragm.  
     
     
       15. An electrosurgical system comprising: 
       an electrosurgical instrument having a handle defining a proximal end of the instrument and by means of which the instrument may be manipulated by a user;  
       a shaft extending from the handle;  
       an active tissue treatment electrode on the shaft which is axially spaced from the handle and which defines a distal end of the instrument;  
       an elongate removable sheath adapted to extend coaxially with, and externally around, the shaft of the instrument, the sheath comprising an outlet port, an opening on the distal side of the outlet port; and  
       sealing means on the proximal side of the outlet port for forming a substantially fluid-tight seal with the instrument, thereby to enable low pressure applied at the outlet port to be transmitted to the distal opening to create suction in the region thereof;  
       wherein the sheath has a first cross-sectional area adjacent to the distal opening, a second cross-sectional area larger than the first cross-sectional area adjacent to the outlet port, and an intermediate section extending axially between the first cross-sectional area and the second cross-sectional area, at least the majority of the intermediate section having an intermediate cross-sectional area that is greater than the first cross-sectional area and smaller than the second cross-sectional area; and  
       wherein the sealing means includes a sealing ring located at the proximal end of the sheath, the sealing ring cooperating with a distal surface on the handle of the instrument to form a seal.  
     
     
       16. An electrosurgical system comprising: 
       an electrosurgical instrument having a handle defining a proximal end of the instrument and by means of which the instrument may be manipulated by a user;  
       a shaft extending from the handle;  
       an active tissue treatment electrode on the shaft which is axially spaced from the handle and which defines a distal end of the instrument; and  
       an elongate removable sheath adapted to extend coaxially with, and externally around, the shaft of the instrument, the sheath comprising an outlet port, an opening on the distal side of the outlet port; and sealing means on the proximal side of the outlet port for forming a substantially fluid-tight seal with the instrument, thereby to enable low pressure applied at the outlet port to be transmitted to the distal opening to create suction in the region thereof;  
       wherein the sheath has a first cross-sectional area adjacent to the distal opening, a second cross-sectional area larger than the first cross-sectional area adjacent to the outlet port, and an intermediate section extending axially between the first cross-sectional area and the second cross-sectional area, at least the majority of the intermediate section having an intermediate cross-sectional area that is greater than the first cross-sectional area and smaller than the second cross-sectional area; and  
       wherein the sheath is made of a translucent material.  
     
     
       17. An electrosurgical system comprising: 
       an electrosurgical instrument having a handle defining a proximal end of the instrument and by means of which the instrument may be manipulated by a user;  
       a shaft extending from the handle;  
       an active tissue treatment electrode on the shaft which is axially spaced from the handle and which defines a distal end of the instrument;  
       an elongate removable sheath adapted to extend coaxially with, and externally around, the shaft of the instrument, the sheath comprising an outlet port, an opening on the distal side of the outlet port, and sealing means on the proximal side of the outlet port for forming a substantially fluid-tight seal with the instrument, thereby to enable low pressure applied at the outlet port to be transmitted to the distal opening to create suction in the region thereof; and  
       an abutment including mutually-engageable surfaces in the instrument and the sheath, wherein when the mutually-engageable surfaces are in engagement, the distal opening of the sheath is located at a predetermined distance from the active electrode;  
       wherein the sheath has a first cross-sectional area adjacent to the distal opening, a second cross-sectional area larger than the first cross-sectional area adjacent to the outlet port, and an intermediate section extending axially between the first cross-sectional area and the second cross-sectional area, at least the majority of the intermediate section having an intermediate cross-sectional area that is greater than the first cross-sectional area and smaller than the second cross-sectional area;  
       wherein the mutually-engageable surfaces are at the proximal end of the sheath and the distal end of the handle; and  
       wherein the mutually-engageable surfaces are a sealing ring located at the proximal end of the sheath and a distal surface on the handle, the sealing ring and the distal surface forming the sealing means.  
     
     
       18. A method of operating an electrosurgical system comprising an electrosurgical instrument having a handle at a proximal end thereof by means of which the instrument may be manipulated, a shaft extending from the handle on which an active tissue treatment electrode is located at a distal end of the instrument, and an electrosurgical generator connected to the active electrode to supply radio frequency power thereto, the method comprising the steps of: 
       sheathing at least a part of the shaft of the instrument in a substantially fluid-tight chamber, the chamber having an opening located in the vicinity of the active electrode;  
       immersing the active electrode and thereby the opening within a liquid;  
       operating the generator to apply radio frequency power to the active electrode, thereby to create bubbles in the liquid; and  
       reducing pressure within the chamber, thereby creating suction at the opening in the region of the active electrode and removing bubbles from the liquid.  
     
     
       19. A method according to  claim 18 , wherein the liquid is an electrically-conductive liquid, the method further comprising the steps of: 
       controlling the output power of the generator to form a vapour pocket around the active electrode; and  
       controlling a flow rate of liquid over the surface of the active electrode occurring as a result of suction at the opening to ensure removal of bubbles from the vicinity of the active electrode, and simultaneously preventing heat removal from the active electrode sufficient to cause quenching of the vapour pocket.  
     
     
       20. A method according to  claim 19 , wherein the flow rate is controlled by the step of locating the opening at a predetermined distance from the active electrode. 
     
     
       21. A method according to  claim 18 , wherein the fluid-tight chamber has a larger internal cross-sectional area at its proximal end than at its distal end, the method further comprising the step of retracting the instrument within the sheath to increase a cross-sectional area of a lumen formed between a distal end of the instrument shaft and the chamber while maintaining suction at the opening of the chamber, thereby to enable the passage of any detritus blocking the lumen away from the opening and towards an outlet port in the chamber. 
     
     
       22. A method according to  claim 21 , wherein the suction at the opening is maintained during retraction of the instrument by virtue of a seal between the instrument shaft and a part of the chamber located proximally of the outlet port. 
     
     
       23. A sheath for an electrosurgical instrument, the sheath comprising an elongate tube having an opening at a distal end through which an active electrode of the instrument may project, and a further opening at a proximal end to enable insertion of the instrument within the sheath, the sheath further comprising an outlet port via which suction may be applied to the interior of the tube and sealing means located proximally of the outlet port, the sealing means comprising a member within the tube having a substantially central aperture through which a shaft of the instrument on which the active electrode is located may project, the member being adapted to form a substantially fluid-tight seal against the shaft, thereby to enable suction applied to the interior of the tube at the outlet port to create suction at the distal opening of the sheath, wherein the tube has a first cross-sectional area adjacent to the distal opening, a second cross-sectional area larger than the first cross-sectional area adjacent to the outlet port, and an intermediate section extending axially between the first cross-sectional area and the second cross-sectional area, at least the majority of the intermediate section having an intermediate cross-sectional area that is greater than the first cross-sectional area and smaller than the second cross-sectional area and that extends a majority of the distance between the outlet port and the distal opening. 
     
     
       24. A sheath according to  claim 23 , wherein the internal cross-sectional area of the tube is greater in the region of the outlet port than at the distal opening. 
     
     
       25. A sheath for an electrosurgical instrument, the sheath comprising an elongate tube having an opening at a distal end through which an active electrode of the instrument may project, and a further opening at a proximal end to enable insertion of the instrument within the sheath, the sheath further comprising an outlet port via which suction may be applied to the interior of the tube, and sealing means located proximally of the outlet port, the sealing means comprising a member within the tube having a substantially central aperture through which a shaft of the instrument on which the active electrode is located may project, the member being adapted to form a substantially fluid-tight seal against the shaft, thereby to enable suction applied to the interior of the tube at the outlet port to create suction at the distal opening of the sheath, wherein the tube has a first cross-sectional area adjacent to the distal opening, a second cross-sectional area larger than the first cross-sectional area adjacent to the outlet port, and an intermediate section extending axially between the first cross-sectional area and the second cross-sectional area, at least the majority of the intermediate section having an intermediate cross-sectional area that is greater than the first cross-sectional area and smaller than the second cross-sectional area, and wherein the sheath is made of a translucent flexible material. 
     
     
       26. An electrosurgical system according to  claim 25 , wherein the sheath tapers from the outlet port to the distal opening. 
     
     
       27. An electrosurgical system according to  claim 25 , wherein the sheath has a stepped internal cross-section. 
     
     
       28. An electrosurgical system comprising: 
       an electrosurgical instrument having a handle defining a proximal end of the instrument and by means of which the instrument may be manipulated by a user;  
       a shaft extending from the handle;  
       an active tissue treatment electrode on the shaft which is axially spaced from the handle and which defines a distal end of the instrument; and  
       an elongate removable sheath adapted to extend coaxially with, and externally around, the shaft of the instrument, the sheath comprising an outlet port, an opening on the distal side of the outlet port, and sealing means on the proximal side of the outlet port for forming a substantially fluid-tight seal with the instrument, thereby to enable low pressure applied at the outlet port to be transmitted to the distal opening to create suction in the region thereof;  
       wherein the sheath has a first cross-sectional area adjacent to the distal opening, a second cross-sectional area larger than the first cross-sectional area adjacent to the outlet port, and an intermediate section extending axially between the first cross-sectional area and the second cross-sectional area, at least the majority of the intermediate section having an intermediate cross-sectional area that is greater than the first cross-sectional area and smaller than the second cross-sectional area; and  
       wherein the intermediate section includes a first section having the first cross-sectional area, a second section having the second cross-sectional area, and a third section extending axially between the first section and the second section having a third cross-sectional area that is greater than the first cross-sectional area, but smaller than the second cross-sectional area, the third section having an axial length greater than the axial length of either the first section or the second section.  
     
     
       29. A sheath for an electrosurgical instrument, the sheath comprising an elongate tube having an opening at a distal end through which an active electrode of the instrument may project, and a further opening at a proximal end to enable insertion of the instrument within the sheath, the sheath further comprising an outlet port via which suction may be applied to the interior of the tube and sealing means located proximally of the outlet port, the sealing means comprising a member within the tube having a substantially central aperture through which a shaft of the instrument on which the active electrode is located may project, the member being adapted to form a substantially fluid-tight seal against the shaft, thereby to enable suction applied to the interior of the tube at the outlet port to create suction at the distal opening of the sheath, wherein the tube has a first cross-sectional area adjacent to the distal opening, a second cross-sectional area larger than the first cross-sectional area adjacent to the outlet port, and an intermediate section extending axially between the first cross-sectional area and the second cross-sectional area, at least the majority of the intermediate section having an intermediate cross-sectional area that is greater than the first cross-sectional area and smaller than the second cross-sectional area; and wherein the intermediate section includes a first section having the first cross-sectional area, a second section having the second cross-sectional area, and a third section extending axially between the first section and the second section having a third cross-sectional area that is greater than the first cross-sectional area, but smaller than the second cross-sectional are, the third section having an axial length greater than the axial length of either the first section or the second section. 
     
     
       30. A sheath for an electrosurgical instrument, the sheath comprising an elongate tube having an opening at a distal end through which an active electrode of the instrument may project, and a further opening at a proximal end to enable insertion of the instrument within the sheath, the sheath further comprising an outlet port via which suction may be applied to the interior of the tube and sealing means located proximally of the outlet port, the sealing means comprising a member within the tube having a substantially central aperture through which a shaft of the instrument on which the active electrode is located may project, the member being adapted to form a substantially fluid-tight seal against the shaft, thereby to enable suction applied to the interior of the tube at the outlet port to create suction at the distal opening of the sheath, wherein the tube has a first cross-sectional area adjacent to the distal opening, a second cross-sectional area larger than the first cross-sectional area adjacent to the outlet port, and an intermediate section extending axially between the first cross-sectional area and the second cross-sectional area, at least the majority of the intermediate section having an intermediate cross-sectional area that is greater than the first cross-sectional area and smaller than the second cross-sectional area, and wherein the intermediate section has a cross-sectional area that continuously tapers down from the second cross-sectional area adjacent to the outlet port to the first cross-sectional area adjacent to the distal opening.